/* *  shcodec ;) version 1.0.1 *  Copyright (C) 1998-2002 Alexander Simakov *  April 2002 * *  This software may be used freely for any purpose. However, when *  distributed, the original source must be clearly stated, and, *  when the source code is distributed, the copyright notice must *  be retained and any alterations in the code must be clearly marked. *  No warranty is given regarding the quality of this software. * *  internet: http://www.webcenter.ru/~xander *  e-mail: xander@online.ru */#include "shc.h"int sh_EncodeBlock(uchar *iBlock, uchar *oBlock, int bSize){    int   freq[SH_MAX_ALPHA];    uchar symb[SH_MAX_ALPHA];    uchar *len, *code, *aux;    int i, j, n, treeSize, streamSize, bits;    uint bitbuf; uint *pBlock;    if (!bSize) return (0);    /* Save block size */    *((int *)oBlock)=bSize;    /* Get symbol freqs */    sh_GetFreq(freq, iBlock, bSize);    /* Sort symbols */    n=sh_SortFreq(freq, symb);    /* Calculate code lengths */    sh_CalcLen(freq, symb, len=(uchar *)freq, n, 31);    /* Sort symbols */    sh_SortLen(len, symb, n);    /* Calculate huffman codes */    code=((uchar *)freq)+SH_MAX_ALPHA;    sh_CalcCode(len, symb, code, n);    /* Pack code tree */    aux=((uchar *)freq)+SH_MAX_ALPHA*2;    treeSize=sh_PackTree(len, symb, aux, (uint *)(oBlock+5), n);    oBlock[4]=(uchar)treeSize;    streamSize=5+treeSize;    bits=31; bitbuf=0;    pBlock=(uint *)(oBlock+streamSize);    /* Encode a stream */    for (i=j=0; i<bSize; i++)    ENCODE_SYMB(len, code, iBlock[i], pBlock, j, bits, bitbuf);    /* Flush remaining data */    bitbuf<<=bits;    pBlock[j++]=bitbuf;    /* Return encoded stream size(in bytes) */    return(streamSize+(j<<2));}int sh_DecodeBlock(uchar *iBlock, uchar *oBlock, int bSize){    uchar len [SH_MAX_ALPHA];    uchar symb[SH_MAX_ALPHA];    uchar base[SH_MAX_CLEN];    uchar offs[SH_MAX_CLEN];    uchar *cache;    int i, j, n, streamSize, treeSize, bits, symbol;    uint bitbuf, *pBlock;    if (!bSize) return (0);    /* Read stream size */    streamSize=*((int *)iBlock);    /* Read packed tree size */    treeSize=iBlock[4];    /* Expand packed tree */    n=sh_ExpandTree(len, symb, (uint *)(iBlock+5));    /* Sort symbols */    sh_SortLen(len, symb, n);    /* Calculate decode tables */    sh_CalcDecode(len, symb, base, offs, cache=len, n);    pBlock=(uint *)(iBlock+treeSize+5);    bits=31; bitbuf=pBlock[0];    /* Decode a stream */    for (i=0, j=1; i<streamSize; i++) {        DECODE_SYMB(base, offs, cache, symb, pBlock, j, bits, bitbuf, symbol);        oBlock[i]=(uchar)symbol;    }    /* Return decoded stream size */    return(streamSize);}